Integrated circuits may suffer undesirable effects caused by charged particles such as alpha particles. Single event effects, which are transient effects cause by a single charged particle passing through silicon, are the dominant type of these undesirable effects. The charged particle produces a current pulse in the silicon that perturbs the operation of the integrated circuit. For example, the current pulse resulting from the charged particle can cause random bit inversion of a storage cell, which is referred to as a single event upset. If the storage cell is part of a register, the bit inversion results in incorrect data being stored in the register, which will cause an error when the register is read. Such an error is sometimes referred to as a soft error, because the storage cell remains functional and can be re-written with new data.
The vulnerability of storage cells to single event effects such as single event upset increases as transistor dimensions shrink and voltage supply levels decrease. Single event effects are therefore becoming an increasingly large source of error in integrated circuits.
Existing techniques for mitigating single event effects suffer from significant performance penalties or die area penalties. Accordingly, there is a need for mitigation techniques that are efficient with regard to both performance and die area.